Why is my plot not working within my for loop?
显示 更早的评论
I am trying to plot multiple helices. With the code I am using (below) the helix is plotting how I want it to, however, only one helix is not plotting. Does anyone know why this may be the case?
clc;
clear variables;
close all;
n = input('number of revolutions ');
r = input('radius of stent ');
a = input('angle with respect to the upwards horizontal in degrees ');
w = input('number of wires ');
R = input('radius of wire ');
h=(2*n*pi*r)/tand(90-a); %height of stent determined by other inputs
e = (2*pi)/(w/2); %theta (spacing between where each wire starts)
if mod(w,2) ==0 %number of wires is even
else
fprintf('ERROR:number of wires must be even'); %stops code if wire number is odd
return
end
if mod(n,1) ==0 %number of revolutions is whole number
else
fprintf('ERROR:number of revolutions must be whole number');
return
end
for i=1:w/2
for t = (i-1)*e:2*pi/w:(n*2*pi)+e*(i-1); %t value for CCW helices
if mod(t,4*pi/w)==0
x{i} = (r-R)*sin(t);
y{i} = (r-R)*cos(t);
z{i} = (h/(n*2*pi))*t(1);
plot3(x{i},y{i},z{i},'.','MarkerSize',25,'MarkerFaceColor','red','MarkerEdgeColor','red')
hold on
else
x{i} = (r+R)*sin(t);
y{i} = (r+R)*cos(t);
z{i} = (h/(n*2*pi))*t(11);
plot3(x{i},y{i},z{i},'.','MarkerSize',25,'MarkerFaceColor','black','MarkerEdgeColor','black')
hold on
end
hold on
end
hold on
end
5 个评论
Could you provide a set of input values so your code can be run?
Off the bat I have a suggestion. You are calling 'hold on' too many times. Prior to your loop you can create the figure and axis and hold it once. This isn't the source of the problem you described, though.
figure;
axh = axis();
hold(axh, 'on')
then you can get rid of all the other 'hold on' lines.
Julia Morandi
2018-7-17
dpb
2018-7-17
A guess would be
if mod(t,4*pi/w)==0
is never actually satisfied for most cases owing to FP rounding...
Julia Morandi
2018-7-17
Adam Danz
2018-7-17
Using those inputs, your code breaks in the 'else' section of your conditional at line
z{i} = (h/(n*2*pi))*t(11);
I'm guessing that t(11) is a mistake.
采纳的回答
Change
z{i} = (h/(n*2*pi))*t(11);
to
z{i} = (h/(n*2*pi))*t(1); %or whatever the index should be
and it works with the inputs you specified in the comment section above.
For inputs [2,20,34,12,1]
4 个评论
Julia Morandi
2018-7-17
It is plotting multiple data sets (wires). It's just plotting directly over top of previous data with an occasional unique data point appearing.
I determined that in debug mode by changing the colors after the first complete iteration of the i-loop.
Another way to test that is to create a new figure at every i-loop iteration.
for i=1:w/2
figure
axis
hold on
for t = (i-1)*e:2*pi/w:(n*2*pi)+e*(i-1); %t value for CCW helices
if mod(t,4*pi/w)==0
x{i} = (r-R)*sin(t);
y{i} = (r-R)*cos(t);
z{i} = (h/(n*2*pi))*t(1);
plot3(x{i},y{i},z{i},'.','MarkerSize',25,'MarkerFaceColor','red','MarkerEdgeColor','red')
else
x{i} = (r+R)*sin(t);
y{i} = (r+R)*cos(t);
z{i} = (h/(n*2*pi))*t(1);
plot3(x{i},y{i},z{i},'.','MarkerSize',25,'MarkerFaceColor','black','MarkerEdgeColor','black')
end
end
end
Here are all 6 'wires'; they appear 2D because the axes aren't rotated.
Julia Morandi
2018-7-17
But they mostly do not change (some do) so something's wrong with you code.
To start, you are currently only storing x,y,z values over the i-loop so you're overwriting a lot of the data making it impossible to look at all of the x,y,z values at once. I changed the code so you store ALL of the data for both i and t loops. If you go this route, you should allocate the x y z data prior to the loops.
figure
axis
hold on
for i=1:w/2
tAll = (i-1)*e:2*pi/w:(n*2*pi)+e*(i-1);
for t = 1:length(tAll); %t value for CCW helices
if mod(tAll(t),4*pi/w)==0
x(i,t) = (r-R)*sin(tAll(t));
y(i,t) = (r-R)*cos(tAll(t));
z(i,t) = (h/(n*2*pi))*tAll(t);
plot3(x(i,t),y(i,t),z(i,t),'.','MarkerSize',25,'MarkerFaceColor','red','MarkerEdgeColor','red')
else
x(i,t) = (r+R)*sin(tAll(t));
y(i,t) = (r+R)*cos(tAll(t));
z(i,t) = (h/(n*2*pi))*tAll(t);
plot3(x(i,t),y(i,t),z(i,t),'.','MarkerSize',25,'MarkerFaceColor','black','MarkerEdgeColor','black')
end
end
end
Now we can look at ALL of the x,y,z values and you can see that there are lots of duplicates. Here I show just the x values. The rows are iterations across the i-loop and the columns are across the t-loop. There are tiny differences between these numbers but they are close enough to be plotted on top of each other. It looks like there are about 6 near-repetitions for each (x,y,z) value and there also happens to be 6 'wires'.
If the values are not what you expect, you'll need to go through your code and figure out what went wrong.
更多回答（1 个）
类别
在 帮助中心 和 File Exchange 中查找有关 Surrogate Optimization 的更多信息
产品
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!
Translated by 
